Australians share a 50,000 year-long history of interacting with their rivers. This presentation focuses on interactions with one particular river: the Hawkesbury. The Hawkesbury River lies ~50 km north of Sydney and is part of the longest coastal river system in NSW, the Hawkesbury-Nepean. The river has an Aboriginal history going back at least 42,000 years, and the catchment is festooned with evidence of Aboriginal occupation: rock engravings, line drawings, and shell middens. The British colonised the river in 1794, a mere six years after the establishment of the colony at Sydney Cove, and within a few decades had managed to almost totally alienate the lands immediately surrounding the river. The rich alluvial flats of the upper Hawkesbury played a critical role in the survival of the early colony, and until the 1820s was the breadbasket for Europeans in NSW. The presentation will discuss various aspects of the way the river has been modified by humans, but equally importantly how it has influenced our society − the way we have variously tried to harness it, work with it or against it, admired it, feared it. The way the river's floodplain was used by Europeans is discussed in detail, with a focus on how they cleared the land and the impacts this had on river navigability and on water quality. The talk then moves onto how the river has acted as a barrier and as a conduit for human movement, and finishes with an overview of how the river has inspired artists, poets and other creative folk since the earliest times. There's also a short section on how the Hawkesbury has maintained great military and strategic importance to Sydney, with military planners from at least the middle of the 19th century considering it a springboard for possible Russian and Japanese invasion of NSW.